Modeling and Analysis of GMD Effects on Power Systems: An overview of the impact on large-scale power systems.

Geomagnetically induced currents (GICs), caused by geomagnetic disturbances (GMDs) (Figure 1), have the potential to affect the operation of interconnected electric power systems. There are two key risks associated with GICs in the bulk electric system. The first is the potential for physical damage to transmission system devices such as high-voltage (HV) transformers. The second is the loss of reactive power support, potentially leading to a voltage collapse. The focus of this article is on the latter risk, presenting an overview of modeling GMDs into the power flow to assess the impact on large-scale power systems.